解决明文响应的Anguar5 HttpClient POST错误

Question

我尝试访问返回明文响应的REST API。但是，当通过Angular5 HttpClient发送请求时，我收到以下错误：

  

解析http://localhost:8080/

期间的Http失败

以下是我的请求的代码：

  login(): void {
    let resultPromise: Promise<string> = login();

    resultPromise.then(token => this.onLogin(token), err => this.onLoginError(err));
  }

  login(loginData: LoginDataService): Promise<string> {
    let registerDTO = loginData.toRegisterDTO();
    const httpOptions = {
      headers: new HttpHeaders({
        responseType: 'text/plain'
      })
    };
    return this.http.post<string>(this.userURL, registerDTO, httpOptions).toPromise();
  }

  private onLogin(token: string): void {
    this.loginData.setToken(token);
    this.router.navigate(["home"]);
  }

  private onLoginError(err: HttpErrorResponse) {
    this.loginData.logout();
    this.errorMsg = err.message;
  }

但是，始终调用onLoginError，传递以下对象：

{
  "headers": {
    "normalizedNames": {},
    "lazyUpdate": null
  },
  "status": 200,
  "statusText": "OK",
  "url": "http://localhost:8080",
  "ok": false,
  "name": "HttpErrorResponse",
  "message": "Http failure during parsing for http://localhost:8080",
  "error": {
    "error": {},
    "text": "fd39196f-08e3-4c54-82dd-99756f544fe2"
  }
}

我发现HttpResponse不包含ContentType标头，即使Chrome显示响应中包含标题。